Nvidia-settings allows you to adjust aniso tropic filtering in the opengl settings.

Ah! Thanks for the tip! Doing some testing it appears that flipping "Image Settings" from "Quality" (default) to "High Quality" does the trick. The aniso texture filter sparkling isn't totally cured, but it's greatly reduced!

(Before I was focused on the Antialiasing Settings space which mentions anisotropic texture filtering -- in particular, the Texture Sharpening toggle, which wasn't doing anything to improve the problem. Image Settings sounded like full-window ops. Probably should be named "Texture Settings". But my bad for not trying all the knobs.

And nvidia-settings supports batch-loading of this setting from a config file, so I can auto-set this on boot-up -- excellent! We'll be using this on our multi-node rendering systems at work ASAP.